强引力透镜系统限制宇宙学模型

发布时间：2018-01-05 08:16

本文关键词：强引力透镜系统限制宇宙学模型　出处：《大连理工大学》2016年硕士论文　论文类型：学位论文

【摘要】：1998年,基于两个小组对Ia型超新星观测的证据表明,我们的宇宙当前正处于一个所谓的“后期加速膨胀”阶段,揭示出这个加速膨胀背后的机制成为21世纪宇宙学最重要的任务之一。目前,对于宇宙加速膨胀有两种诠释路径,分别是暗能量假说和大尺度上的修改引力理论。具有负压强的暗能量假说是建立在对爱因斯坦广义相对论信任的基础上的,甫一提出便引起了广大研究者们的关注,持这种观点的人们认为正是暗能量的负压强为宇宙加速膨胀提供了动力。此外,从宇宙的组成成分上来看,最新的观测数据显示,普通物质占宇宙组分的4%,影响宇宙演化和大尺度结构形成的暗物质占28%,为宇宙加速膨胀提供驱动力的暗能量占68%,其中后两者都是不与光相互作用(看不见)的暗成分,由此数据我们确信暗成分对宇宙演化起到了决定性作用,而我们恰恰对它们知之甚少。为了破解这个僵局,揭开暗能量的神秘面纱并进一步解释宇宙后期加速膨胀现象,宇宙学家们做了很多努力。在理论方面,提出了各种各样唯象的暗能量模型。其中把暗能量状态方程参数化或者常数化的ωCDM模型作为标准的基于宇宙学常数的ACDM模型的简单推广,在理论上具有重要研究价值。观测方面,强引力透镜作为宇宙学领域的一颗新星正在受到越来越广泛的重视。当前来自多个观测项目的强引力透镜系统数据已达到118组,研究它们对暗能量模型的限制是一件很有意义的工作。本文的主要工作就是利用118组强引力透镜系统来限制暗能量状态方程为常数的wCDM模型。利用马尔可夫链-蒙特卡洛(MCMC)方法,对宇宙学参数和透镜模型参数进行拟合,得到了相对紧致的参数空间,验证了宇宙学参数与强引力透镜模型之间的依赖关系,并讨论了幂律模型中幂律指数7的两种参数化形式对宇宙学参数的影响。本文具体分为三章,我们的主要工作放在了第三章。在第一章我们阐述了必要的背景宇宙学知识,使得我们能够无障碍地在后续部分展开对强引力透镜的介绍,主要包括宇宙背景动力学演化相关的知识,观测中常用的红移和角直径距离的概念,以及几种流行的暗能量模型。在第二章中,我们介绍强引力透镜的基本理论,首先假设强引力透镜可以近似为奇异等温球(SIS)模型,进一步我们推广到更一般化的幂律密度(PLP)模型,并给出模型理论与观测之间的数学关系。在第三章中我们用来自SLACS、BELLS、LSD和SL2S的118组强引力透镜系统限制wCDM模型。角直径距离的比值Dobs= D(zl,zs)/D(O,zs)作为宇宙学观测量,通过MCMC方法,拟合得出最优的模型参数空间并给出对结果的分析。本文的最后部分是我们的总结。
[Abstract]:In 1998, two groups of observations of type Ia supernovae based on the evidence that our universe is currently in a so-called "accelerated expansion" stage, revealing the mechanism behind this acceleration has become one of the most important tasks of cosmology in twenty-first Century. At present, the accelerated expansion of universe two interpretation path, respectively. Is dark energy hypothesis and large scales. The modified gravity theory has dark energy negative pressure hypothesis is based on Einstein's theory of general relativity on the basis of trust, was proposed, has aroused widespread attention of researchers, people who hold this view that it is the negative pressure of dark energy is accelerating expansion of the universe provide power. In addition, from the point of view of the composition of the universe, the latest observations showed that ordinary matter component of the universe 4%, affecting the formation of large scale structure of the universe and the evolution of dark matter accounts for 28 %, provide the driving force of the dark energy accounted for 68% of the accelerating expansion of the universe, after which both are not interact with light (invisible) dark component, the data on the evolution of the universe, we are sure that the dark component plays a decisive role, and we just know little about them. In order to break this impasse. Mysterious dark energy and further explain the late acceleration phenomenon, astronomers have made a lot of efforts. In the theoretical aspect, put forward various phenomenological models of dark energy. The dark energy equation of state parameters or constants of the Omega CDM model as the standard simple extension of the ACDM model of the cosmological constant based on the important research value in theory. Observation, strong lensing as a new star in the field of cosmology is attracted more and more attention. The strong gravity from multiple projects through observation Mirror system data has reached 118, on the restriction of the dark energy model is a very meaningful work. The main work of this paper is to use 118 sets of strong gravitational lens systems to limit the dark energy equation of state for wCDM model constant. Using Markov chain Monte Carlo (MCMC) method to fit the cosmological parameters the lens and the parameters of the model, get the parameter space is relatively compact, verify the dependencies between the cosmological parameters and strong lensing model, and discussed the effects of two kinds of parametric form of the power-law index of the power law model of the universe in 7 parameters. This paper is divided into three chapters, the main work we put in in the third chapter. In the first chapter, we elaborate the necessary background knowledge of cosmology, so that we can start without hindrance on strong gravitational lensing in the subsequent introduction part, mainly includes the dynamic background of the universe The evolution of knowledge, redshift and the angular diameter distance of the common concept of observation, and several popular models of dark energy. In the second chapter, we introduce the basic theory of strong gravitational lensing, assuming strong lensing can approximate the singular isothermal sphere (SIS) model, we further extended to power-law density generalized (PLP) model, the mathematical relationship between model theory and observation was given. In the third chapter we use from SLACS, BELLS, LSD and SL2S of the 118 groups of strong gravitational lens system to limit the wCDM model. The angular diameter distance ratio Dobs= D (ZL, ZS) /D (O, ZS) as cosmology the measurements by the MCMC method, the fitting results of the analysis of the results of the optimal model parameter space is given. In the last part of this paper is our summary.

【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P159

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